Carbon dioxide snow hood

Abstract

A carbon dioxide snow hood is disclosed for separating gaseous and solid carbon dioxide particles and depositing a uniform blanket of the carbon dioxide particles in the form of snow on articles to be cooled.

What is claimed is: 
     
       1. A snow hood for depositing carbon dioxide snow on a product comprising: (a) an exhaust housing having an open bottom,   (b) a reversing diffuser chamber within said exhaust housing having side walls, a closed upper end, and an open bottom,   (c) means for separating a two-phase flow of gaseous and solid carbon dioxide into separate high velocity streams of gaseous and solid carbon dioxide, and   (d) means for directing said high velocity stream of solid carbon dioxide upwardly into said reversing diffuser chamber whereby said stream is reversed, diffused and reduced in velocity to form a dispersed, downwardly flowing, low velocity stream of carbon dioxide snow.   
     
     
       2. The snow hood as claimed in claim 1 including drip rails positioned at the lower edge of the walls of the reversing diffuser chamber for collecting condensation. 
     
     
       3. The snow hood as claimed in claims 1 or 2 where means (c) comprise a separator tube, and means (d) comprise a slot and flow directing shield. 
     
     
       4. The snow hood as claimed in claim 1 including means for directing the high velocity stream of separated carbon dioxide gas upwardly within said exhaust housing to aspirate a flow of warm ambient air upwardly through said exhaust housing, means for mixing said warm air and cold carbon dioxide gas, and discharge means in the top of said exhaust housing for discharging said mixture of gaseous carbon dioxide and air. 
     
     
       5. The snow hood as claimed in claim 4 including diffuser means for reducing the velocity of the gaseous carbon dioxide stream and promoting thorough mixing thereof with the ambient air prior to discharge of the mixture from said snow hood.